How it works
1 mil = 0.001 in = 0.0254 mm = 25.4 µm. Inches = mils ÷ 1,000. Mils = inches × 1,000.
- Choose mils to inches or inches to mils.
- Enter the thickness as a non-negative decimal.
- Read the exact result, millimetres and microns.
Worked example: 6 mil plastic is 6 ÷ 1,000 = 0.006 inches thick. That is exactly 0.1524 mm, or 152.4 µm. Three mil is exactly 0.003 inches.
Common mil thicknesses
| Mils (thou) | Inches | Millimetres equivalent | Microns equivalent |
|---|---|---|---|
| 1 | 0.001 in | 0.0254 mm | 25.4 µm |
| 2 | 0.002 in | 0.0508 mm | 50.8 µm |
| 3 | 0.003 in | 0.0762 mm | 76.2 µm |
| 4 | 0.004 in | 0.1016 mm | 101.6 µm |
| 5 | 0.005 in | 0.127 mm | 127 µm |
| 6 | 0.006 in | 0.1524 mm | 152.4 µm |
| 8 | 0.008 in | 0.2032 mm | 203.2 µm |
| 10 | 0.01 in | 0.254 mm | 254 µm |
| 20 | 0.02 in | 0.508 mm | 508 µm |
| 100 | 0.1 in | 2.54 mm | 2,540 µm |
| 1000 | 1 in | 25.4 mm | 25,400 µm |
Swipe the table sideways to see the rest.
All values use the exact thousandth-of-an-inch definition.
Things to consider
- Plastic sheeting and vapour barriers often list mil thickness.
- Garbage bags and laminating pouches may use mils.
- Common pouch thicknesses include 3, 5 and 10 mil.
- Check whether a pouch rating is per side.
- Paint, coatings and wire insulation use thickness measurements.
- Check PCB trace and feeler gauge specifications carefully.
- Gauge depends on the material, not one fixed factor.
Frequently asked questions
How many mils are in an inch?
There are exactly 1,000 mils in one inch. Divide mils by 1,000 to get inches, or multiply inches by 1,000 to get mils. Half an inch is 500 mil.
Is a mil the same as a millimetre?
No. In this converter, one mil is 0.0254 mm. One millimetre is about 39.3701 mils. Slang can use mil for millimetres or millilitres, and navigation or optics can use an angular mil. Confirm the intended unit. For millimetres to inches, divide your mm value by 10 and use the Centimetres to Inches Converter.
What is the difference between a mil and a micron?
A micron is a micrometre, written µm, equal to one thousandth of a millimetre. A mil is one thousandth of an inch, exactly 25.4 µm. Ten mil equals 254 µm.
How thick is 6 mil plastic?
Six mil is exactly 0.006 inches, 0.1524 mm or 152.4 µm. Plastic sheeting and vapour barriers may use this thickness, but suitability depends on the product and local requirements.
Can I convert mils to gauge?
Not with a single fixed conversion. Gauge varies by material and rating system, including sheet metal, wire and plastic. Use the manufacturer's thickness table for that product rather than assuming one universal gauge factor.
Where are mil thicknesses used?
Examples include garbage bags, laminating pouches, paint and coating films, wire insulation, PCB traces and feeler gauges. Product ratings can have different meanings, so check whether they describe one layer, one side or a total thickness.
Results are estimates for general information only, not financial, medical or professional advice.